Can you unscramble the following letters to produce a phrase relevant to US history? It's the first half of US history, i.e., up through the Civil War.

ostetnfrcAiesWsi

I subbed a US History class today and this was one of the assignments for the students. They spent all hour on it and didn't come up with it. I admit that I'm stumped. But I think it might be three words with the middle word "of" ... or not.